The present disclosure relates to a filler neck closure system for a fuel tank, and particularly to a filler neck closure for use in a vehicle fuel tank filler neck. More particularly, the present disclosure relates to closure seals and vent valves for use in a filler neck closure assembly.
A fuel-dispensing pump nozzle provided at a filling station is operated to dispense liquid fuel into a vehicle fuel tank filler neck during a tank-refueling activity. Pump nozzles are known to include a fill-limiting sensor and a shut-off mechanism coupled to the sensor and configured to shut off the flow of fuel from the nozzle into a fuel tank filler neck whenever the tank is full and liquid fuel “backs up” the filler neck to splash onto or reach the fill-limiting sensor located on the nozzle.
Ordinarily, fuel vapor vent valves associated with the fuel tank close automatically once the tank is filled to capacity. Fuel vapor pressure increases in the tank once the fuel vapor vent valves close as long as fuel is still being pumped into the tank through the filler neck. This increased “tank” pressure displaces liquid fuel in the tank causing some liquid fuel to move upwardly in the filler neck in a direction toward the fuel-dispensing pump nozzle that is arranged to extend into the mouth of the filler neck. The upwardly moving liquid fuel reaches the nozzle and actuates a shut-off mechanism or sensor associated with the pump nozzle.